1. Field of the Invention
The present invention relates to a memory element. In particular, the present invention relates to a memory element where data is stored in a node which is brought into a floating state by turning off a transistor a channel of which is formed in an oxide semiconductor layer. The present invention relates to a semiconductor device (e.g., a programmable logic device) including the memory element.
2. Description of the Related Art
Transistors using an oxide semiconductor as a material of an active layer have been developed. For example, Patent Document 1 discloses a memory element where data can be stored in a node which is brought into a floating state by turning off the transistor. Note that the memory element has a nonvolatile property (see paragraph 0044 in Patent Document 1).